Problem 96 - Advanced Problems in Organic Chemistry for Competitive Examinations

Question

Which one of the following is a protein fibre? (a) Rayon (b) Cotton (c) Silk (d) Polyester

Step-by-Step Solution

Answer

Silk is a protein fibre.

Step 1: Identify the Type of Fibres

To determine which option is a protein fibre, we first need to understand what a protein fibre is. Protein fibres are natural fibres composed of proteins. These are typically found in animal hairs, such as wool or silk.

Step 2: Analyze the Options

Now, let's explore each option: - Rayon: It is a semi-synthetic fibre made from cellulose (a plant material), not a protein. - Cotton: It is a natural fibre obtained from the cotton plant; hence, it is a carbohydrate fibre (cellulose), not a protein. - Silk: It is a natural fibre produced by the larvae of the silkworm and is composed of proteins. - Polyester: It is a synthetic fibre made from petrochemicals, not a protein.

Step 3: Determine the Correct Answer

Among the options given, Silk is derived from animals and is composed of proteins, making it a protein fibre. Hence, Silk is the only option that qualifies as a protein fibre.

Key Concepts

Protein Fibres

Protein fibres are fascinating components in the world of textiles and materials. These fibres are unique because they naturally occur and come from proteins in animals. The two most well-known protein fibres are silk and wool.
Unlike plant-derived fibres (such as cotton or linen), protein fibres have specific properties like elasticity, strength, and a natural sheen.

• Elasticity: They can stretch without breaking, which makes them durable.
• Strength: Protein fibres are strong and can bear stress.
• Sheen: Often, they have a shiny look, making them attractive choices for high-end fabrics.

Protein fibres are integral to many textile applications, from clothing to upholstery, due to these properties. They are not only valued for their physical characteristics but also their luxurious feel and appearance.

Natural Fibres

Natural fibres are sourced directly from nature, often requiring minimal human processing to be turned into usable materials. These can be classified into two main types: protein fibres and cellulose fibres.
Cellulose fibres come from plants, such as cotton and linen, while protein fibres like silk and wool come from animals. Here’s what makes natural fibres special:

• Renewable: Since they come from plants and animals, they can be replenished naturally over time.
• Biodegradable: Natural fibres decompose more easily compared to synthetic fibres, reducing environmental impact.
• Comfortable: Often, natural fibres breathe well, allowing for more comfort in clothing.

Natural fibres have been used since ancient times and are still popular today for sustainable and environmentally-friendly textile production.

Silk

Silk is an exceptional protein fibre known for its smooth texture and lustrous appearance. Produced by silkworms as they spin their cocoons, silk is a continuous filament fibre unique in the textile world.
Let’s delve into some key characteristics that make silk special:

• Luxurious Feel: The soft and smooth texture of silk is unparalleled, making it a favorite for high-end clothing.
• Natural Shine: Its inherent sheen comes from the triangular prism-like structure of the fibre, which refracts light.
• Temperature Regulation: Silk is breathable and can regulate temperature, keeping wearers cool in summer and warm in winter.

Silk's unique properties have made it a staple in fashion, interior decoration, and even medical applications. It truly is a versatile material with a timeless appeal.

Synthetic Fibres

Synthetic fibres differ significantly from their natural counterparts as they are created through chemical processes rather than sourced directly from nature. Typical examples include polyester, nylon, and acrylic.
Unlike natural fibres, synthetic fibres are often engineered to possess specific desirable properties, such as:

• High Durability: Synthetic fibres are often resistant to wear and tear, making them long-lasting.
• Water Resistance: Many synthetic fibres repel water, which is useful in outdoor and active wear.
• Cost-Effective: Often cheaper to produce than natural fibres, making them accessible for various applications.

Synthetic fibres have modernized textile manufacturing, offering alternatives to traditional fibres and allowing for innovations in fabric technology. Despite their benefits, considerations regarding environmental impact and sustainability continue to shape their development and use.